Measurement of turbulence intensity profile by a mini‐sodar

Abstract

AbstractLow‐level turbulence can bring about rapid bumps and jolts to an aircraft. In severe turbulence, the aircraft may suffer momentary loss of control. In accordance with the practice of the International Civil Aviation Organization (ICAO), turbulence intensity is expressed in terms of the cube root of the eddy dissipation rate (EDR). Measurement of the EDR is an important component in the provision of turbulence alerting services for arriving and departing aircraft at an airport. This article describes a method to calculate the EDR profile using the wind measurements from a ground‐based mini‐sodar located near the Hong Kong International Airport (HKIA). The method makes use of the vertical wind data at 0.25 or 0.5 Hz provided by the mini‐sodar (depending on the maximum measurement range) and searches for the inertial sub‐range in the frequency spectrum of the vertical wind. The accuracy of the wind and EDR measurements of the mini‐sodar is first established by comparison with meteorological tower data in a field experiment. The potential application of the EDR profiles in terrain‐disrupted airflow at HKIA is then demonstrated through two case studies. The EDR profiles obtained from the mini‐sodar are found to be of good quality and could be useful in the monitoring of low‐level turbulence for aviation applications. Copyright © 2008 Royal Meteorological Society